Apple (AAPL) filed a U.S. trade complaint that seeks to block imports of Samsung Electronics’s Galaxy S mobile phone and Galaxy Tab computer, days after asking a federal court to halt sales of the devices.

The complaint submitted Tuesday with the U.S. International Trade Commission in Washington counters patent-infringement claims Samsung filed at the agency last week that seek to block imports of Apple’s iPhone and iPad. Cupertino-based Apple claims Samsung is infringing seven patents related to the technology and design of the devices.

Apple, which has accused competitors of “widespread imitation,” has taken particular aim at Suwon, South Korea-based Samsung, which had been a supplier of chips for some Apple devices. The ferocity of the legal dispute that began in April, which now includes cases in at least four countries, is surprising because the companies are partners, said Brian Marshall, an analyst with Gleacher in San Francisco.

“It has become very public and very ugly, very quickly,” he said. “They’re just going after each other’s throats.”

Marshall said a ban on Samsung imports is unlikely. He expects the companies to reach a settlement and cross-licensing deal. He said that while Apple has been reluctant to license its intellectual property, the company “may not have a choice” in this case because Samsung has so many patents Apple may need.